Turbo M20 2.8L Stroker w/ 135mm rods

[ForcedFirebird]

Have a good time.
I will get out of the way, so you can discuss all this nonsense you discuss anyways in this thread.

By the way:
Real info is on the 402 meter strip.

...and? I was building muscle cars before I got an e30, hence the ForcedFirebird (aka turbo Firebird). You think I have no 1/4mi experience? lol.

It's just more fun to have three of four "402's" in every lap for hours on end, rather than 2-3 runs all night.

[digger]

Right. But you should have addressed this to the EngineBuildingBird, not to me. I am on your side on this issue.

I'm not on anyone's side other than the engine, keep the engine happy I say. There is more than one way to skin a cat.

If I was doing the budget 2.8l I would deck the block as it's the best way with parts at hand , if I wanted to build a 3.1l I'd get a different block as option 1 mainly to build it in parallel and keep car on the road, option 2 would be a thicker gasket. Others may choose other options it's their perogative

[apostate]

Have a good time.
I will get out of the way, so you can discuss all this nonsense you discuss anyways in this thread.

By the way:
Real info is on the 402 meter strip.

[ForcedFirebird]

This apostate dude has always been a D bag. IDK why you keep combating the most knowledgeable people on this forum... Seriously, you're so fucking annoying dude.

You've said that before, yet here we are. You buzz around people like an annoying mosquito.

Glad I'm not the only one.

Just a note.

An American "engine builder" tried to educate me.
Pathetic.

"Dude", what I have built you cannot even imagine.

Good night. I will bother no one no more.

Good. Maybe you will come back with some real info, rather than just arguing with everyone. And please by all means, entertain my curiosity of these imaginable things.

BTW you are also in America, we live in the USA.

[MrBurgundy]

Just a note.

An American "engine builder" tried to educate me.
Pathetic.

"Dude", what I have built you cannot even imagine.

Good night. I will bother no one no more.

You've said that before, yet here we are. You buzz around people like an annoying mosquito.

[apostate]

Just a note.

An American "engine builder" tried to educate me.
Pathetic.

"Dude", what I have built you cannot even imagine.

Good night. I will bother no one no more.

[MrBurgundy]

Right. But you should have addressed this to the EngineBuildingBird, not to me. I am on your side on this issue.

This apostate dude has always been a D bag. IDK why you keep combating the most knowledgeable people on this forum... Seriously, you're so fucking annoying dude.

[ForcedFirebird]

No, just trying to deliver the obvious commonsense to the regular user.
You might have built a lot of engines but it doesn't mean that you built them right, no? It is a great mistake to deck the block and I am sure a lot of people will regret your advice at a later stage when they decide to go after a bigger displacement after finding that there are better options than 2.8L.
With regard to Digger, are you his assistant/secretary? I don't mind talking to the "staff" if the "boss" is alright with it.

Dude, if my engines are winning races, WTF more proof do you need? You think the work load would be what it is here if they didn't last? Proof is in the pudding, I have thousands of dyno graphs to proof my ideas, whereas you just have keyboard diarrhea.

Digger and I have been conversing about these engines for a decade, it's only natural for two people who approach things scientifically to come to the similar conclusions.

Exactly have many m20's have you built? I'm sure I could look at shop records and site a number.

BTW Just went and measured the "0" punched in the block. Difficult to measure so I pressed a piece of tin solder in it and came up with just over ~.010 (2.5mm). So, an extra shave is not going to be the death of the OP's block - specially if he was to take the max .010 and take the rest off the head. I rather leave the heads as full height as possible, though, since shaving it removes the quench band.

Man this is getting way over my head, but I'm glad that you guys have responded so I can learn a little bit.

I took my block to the machine shop today. He is going to acid bath it and mic it this week. Once he measures the bore I will order the proper sized pistons, hopefully I can stick with the standard 84mm bore, as I'd really like to have a square engine.

According to you guys there is so much more that goes into this however, and quench/swirl and Deck height in relation to the pistons are something I am not too familiar with.

What do I need to do as far as quench/swirl? Just tell my piston manufacturer I am using an 885 head and they will handle it? Do they need to know my deck height or something?

Also, I think I'd like to go with 9:1 compression, being that I will be full time E85 and can take advantage of the higher compression without worrying about too much detonation. Do you guys see any downsides to this? Or suggest a better ratio?

If I haven't mentioned it before, I will be attempting to make 500-600whp on this engine, and It will be used in a car that will see a few drift events a year.

Thanks again guys!

A basic stock b25 rebuild with factory matching forged pistons, Bimmerheads dual pattern regrind, and a p6267 just pulled 518whp/550tq at 19psi locally, so don't sweat obtaining those numbers with your stroker.

As far as quench, with a boosted engine, it is more important than N/A as it reduces hot spots and potential detonation. To get a good quench, square and deck the block, bore it, replace the intermediate shaft bearings (be cautions and make sure your machinist understands the procedure). Then you will fit your pistons/crank/rods. Finally you will want to use a sacrificial head gasket (only thing VR gasket is good for lol) and torque it down with used bolts, but before mounting it, place a pieces of solder on the angle part of the piston. Some people like to use clay, but I find the solder is easier to measure (not a bad idea to also do the piston to valve clearance at this time). If the solder is more than .037" by a good margin, shave the head to match.

For pistons, just use the factory style with the raised wrist pin to compensate for the longer rods, and factory dome, you won't need anything special. Many piston MFGR's already have the files to avoid a custom piston fee.

Did you have a MFGR in mind already?

EDIT: Missed the part about compression. Go with as much as your tuner feels comfortable with, but I haven't had an issue going as high as 10:1. Local here has an e39 m5 with stock compression (never opened, 11:1), and is making 780whp @1bar with only meth for charge cooling (no FMIC).

[apostate]

Right. But you should have addressed this to the EngineBuildingBird, not to me. I am on your side on this issue.

[digger]

No, just trying to deliver the obvious commonsense to the regular user.
You might have built a lot of engines but it doesn't mean that you built them right, no? It is a great mistake to deck the block and I am sure a lot of people will regret your advice at a later stage when they decide to go after a bigger displacement after finding that there are better options than 2.8L.
With regard to Digger, are you his assistant/secretary? I don't mind talking to the "staff" if the "boss" is alright with it.

Also common sense is you can use a thicker mls gasket to if you have a good block you want to reuse and getting another is not an option. They aren't cheap but neither is a set of new forged Pistons and another full rebuild.

[SLEEPYDUB]

Man this is getting way over my head, but I'm glad that you guys have responded so I can learn a little bit.

I took my block to the machine shop today. He is going to acid bath it and mic it this week. Once he measures the bore I will order the proper sized pistons, hopefully I can stick with the standard 84mm bore, as I'd really like to have a square engine.

According to you guys there is so much more that goes into this however, and quench/swirl and Deck height in relation to the pistons are something I am not too familiar with.

What do I need to do as far as quench/swirl? Just tell my piston manufacturer I am using an 885 head and they will handle it? Do they need to know my deck height or something?

Also, I think I'd like to go with 9:1 compression, being that I will be full time E85 and can take advantage of the higher compression without worrying about too much detonation. Do you guys see any downsides to this? Or suggest a better ratio?

If I haven't mentioned it before, I will be attempting to make 500-600whp on this engine, and It will be used in a car that will see a few drift events a year.

Thanks again guys!

[apostate]

...

You seem to keep rebutting my posts (as well as Digger's), but I do build these day in and day out for a living, and have owned an e30/m20 specialty shop for almost a decade (have been rebuilding engines in general since 96, once I bough an e30 in 07, that just so happens the direction my shop took). I measure these engine daily, dyno them several times a year and have taken the time to flow the heads on my bench, figured out the best combinations, and my engines are lasting and have racers on podiums etc. My Spec rebuilt 2.5 engines make more power than is allowed in the series, even.

I don't just re-iterate stuff I read on the internet. I have developed my knowledge of these engine by building them, testing them, and racing them, not reading about them.

No, just trying to deliver the obvious commonsense to the regular user.
You might have built a lot of engines but it doesn't mean that you built them right, no? It is a great mistake to deck the block and I am sure a lot of people will regret your advice at a later stage when they decide to go after a bigger displacement after finding that there are better options than 2.8L.
With regard to Digger, are you his assistant/secretary? I don't mind talking to the "staff" if the "boss" is alright with it.

[ForcedFirebird]

Then use a thinner mls gasket to tune the piston to head clearance and avoid having to take a lot off the block

The Pistons don't sit 0.5mm below deck with that combo, it's 0.5mm below stock which is already above. Not optimising the piston to deck clearance is doing half a job

True, could use thinner gasket, Cometic actually offers a .040" which will get you close, but again it's a moot point since a $200 gasket costs more than a replacement block. .5mm is not as much as one thinks to take off a block (it often takes .1-.2mm to square and fresh the deck anyways).

Unlike the budget b27 build which pulls 5mm off and can move the cam timing. If you look at an m20 block it has a "10" stamped on the front corner as a machining limit guide. When machining it the "1" comes off first, then the "0" which happens right before .5mm, so realistically you are only a very slight past factory machining limit for a rebuild.

Excuse the imperial measurements, but all my measuring tools are. I recently took .010" off a block and the head was only .004" shorter than stock and I still had .057" quench with the stock gasket (found the domed pistons most power at .037"). The "0" was still showing clear as day. I let the engine go since we were close to race day and it still made more power than Spec allows.

[digger]

Then use a thinner mls gasket to tune the piston to head clearance and avoid having to take a lot off the block

The Pistons don't sit 0.5mm below deck with that combo, it's 0.5mm below stock which is already above. Not optimising the piston to deck clearance is doing half a job

[ForcedFirebird]

What if he decides in the future to go to a 3-3.1-3.2L stroker (as I did)?
Will the decking of the block seem a very good solution then?
CR is achieved through pistons, not through decking of the block or shaving the head.

Um, when your pistons are .5mm below deck, it's got 2.3mm quench seeing you have another 1.7mm in head gasket material, that puts the pistons 2.3mm below the block deck. You build the block to suit and if done correctly the engine will last a good long time, you don't leave power on the table "just in case I want to rebuild it again". The m20b25 was actually designed around the quench/swirl and the reason a flat piston b27 eta with an 885 head will never make the power of a b25.

Besides, m20 block are cheap as chips, why would you try and save $100 on a multi-thousand dollar build? Crap, I have 6 of them on the pallet to be machined, have 4-5 spare rotating assembly cores, 4-5 good running stock m20's, piles of heads etc - and that's just the m20's. Won't go into the mountain of 24v work piled up here.

You seem to keep rebutting my posts (as well as Digger's), but I do build these day in and day out for a living, and have owned an e30/m20 specialty shop for almost a decade (have been rebuilding engines in general since 96, once I bough an e30 in 07, that just so happens the direction my shop took). I measure these engine daily, dyno them several times a year and have taken the time to flow the heads on my bench, figured out the best combinations, and my engines are lasting and have racers on podiums etc. My Spec rebuilt 2.5 engines make more power than is allowed in the series, even.

I don't just re-iterate stuff I read on the internet. I have developed my knowledge of these engine by building them, testing them, and racing them, not reading about them.

That's my point too.
Internet is a great place to learn from but there are people there who know a thing or two about alloys. And about metallurgy science.
Otherwise, it is great to learn from the internet.